Facebook: water efficiency at Prineville is good, but not good enough

Facebook has made a lot of the fact that its Prineville, Ore. data center will be a model of energy and resource efficiency. Now it has some numbers — well, one number — to show how stingy it’s being with water.

A year after adding water metering to its Prineville 1 data center, the company claims a WUE (water usage efficiency) rating of 0.22 liters per kilowatt-hour (L/kWh) for that building. WUE is one of several metrics formulated by The Green Grid to show just how efficient a data center really is. Since the goal is to save water, the ideal WUE value — the ratio of annual water usage to the amount of energy consumed by IT equipment — is zero.

We think that 0.22 L/kWh is a great result, but it should be noted that the WUE concept is fairly new and, to our knowledge, no one else has publicly reported WUE yet. We hope that other companies will soon start measuring and reporting WUE so we can begin setting benchmarks for the metric and working together to find new ways to improve.

While many data centers use water to cool data center equipment, Prineville 1 features a mechanical system with a penthouse that “utilizes 100 percent outside air economization with a direct evaporative cooling and humidification (ECH) misting system. This design allows us to achieve a strong WUE,” according to the post.

The WUE rating does not factor in water used by people — for bathroom or office plumbing — but Facebook says it uses reclaimed water where possible (as well as waterless urinals) to minimize that usage. The company said WUE data for the second Prineville will come out next year when that building goes online and it will also produce WUE metrics for its Forest City, N.C. data center.